The invention relates to a process for indicating and controlling speed and load of mobile chopping machines and an apparatus for realizing this process.
Mobile chopping machines are used for cutting and chopping or picking-up and chopping of plants--rough fodder, corn, etc.--as well as for blowing them into a transport vehicle or for their continuous or periodical transfer. To take in crops at the optimal time within the shortest period, manufacturers increase the output of the engines and the capacity of the machines. It seens to be very important to use the capacity of the given construction in full degree, but at the same time to ensure the required working quality and technological working safety, as well as to blow the crops at a minimal waste into the transport vehicle, whereas these result in a decline of the specific use of energy.
Drivers of up-to-date automotive engines try to carry out this task in such a manner, that on one hand the driver watches plant-stock before the machine and tries to adjust the speed according to the expected load on the basis of the plant-stock's yield and its condition. On the other hand the driver watches the tachometer as well, and when the rotational speed of the chopping drum falls, he slows down the machine, thereby reduces the load and prevents the machine from clogging, which can be obviated only in lost time.
Up-to-date mobile chopping machines--including automotive machines--have not any automatic device securing their working with the required optimal load and preventing from overload, or from clogging or fall of rotational speed of the chopping drum as a result of overload. Due to different construction and function of chopping machines and combines the load control worked out for combines and solutions known from patent specifications relating to this matter (e.g. DE-OS No. 2 106 970, DE-OS No. 2 200 133, DE-PS No. 1 265 476 and U.S. Pat. No. 3,606,742) cannot be adopted to chopping machines, as several tasks should be simultaneously solved for their suitable and economical working, such as
to ensure the maximal turning-out or working load,
to prevent the chopping drum from the extreme fall of rotational speed (to avoid the increasing length of chaffs and the fall of working quality),
to drive the machine at a steady or roughly steady speed (to blow the crop into a transport vehicle or transfer it at a reduced waste),
to ensure the minimal specific use of fuel,
to prevent the machine from clogging.
A driver can carry out the above tasks in dependence of his tiredness, skill and economical interest at a rather different range. That is why it is very important to carry out these tasks with automatization. Till now we have not any such automatization before which would carry out these--in some respect totally opposite tasks, such as maximal output, optimal drum rotational speed, steady speed and minimal specific use of fuel.
Looking at the characteristic diagram of an up-to-date Diesel engine (see FIG. 1) it turns out that engine of chopping machine gives maximal output at a minimal specific use of fuel, when it works with full charge in a scale of rotational speed between n.sub.2 and n.sub.3 --which is the optimal working factor. In case of given engine-type and chopping machine, rotational speed n.sub.2 and n.sub.3 should be determined in such a way that sufficient momentum and reserve range of rotation should be applicable to overcome sudden load increase.
The rotational speed of the chopping drum belonging to the value of n.sub.2 of the engine is a so-called permissible minimal chopping drum speed.
The GB-PS No. 1 605 036--the nearest solution to our invention, described an equipment, where the harvesting machine has a rotation sensor connected to the harvesting device of the machine and a moving-speed sensor, and the automatic speed change is directed to difference reduction of signals given by the two sensors.
In known chopping machines beside a moving speed sensor a rotation sensor can be found as well connected e.g. to the driving machinery of the gathering unit. This equipment could be suitable for avoiding the overload of a chopping machine but because of the permanent speed change it cannot ensure that at the permissible or acceptable degree of load the chopping machine moves with the adjusted speed, therefore it makes the transport vehicle difficult to move with chopping machine together, so crop waste during the blowing into the transport vehicle increases.
The aim of the invention is to develop a process and an apparatus, which ensures
optimal utilization of capacity of a mobile chopping machine and prevention from overload,
operation of said machine with approximately steady speed,
minimal crop waste during blowing and transfer and
prevention from clogging.
Solution according to our invention is based on that recognition that speed and working load of chopping machine can be controlled advantageously on the basis of at least two parameters--suitably speed and rotational speed of the chopping drum--or of three parameters--speed, rotational speed of the chopping drum and momentum of driving machinery of units before the chopping drum--in such a way, that, when rotational speed of the chopping drum increases over its permissible minimum, a speed control is carried out--speed fall due to increase in working load is compensated by a reduction of gear transmission of driving machinery--accordingly the adjusted speed is held but in case of overload, when rotation of the drum falls below the permissible minimum, and/or momentum of driving machinery of units before the chopping drum increases over the adjusted maximum, speed control is discontinued, i.e. a speed decreasing intervention is done, therefore the permissible working load of chopping machine is held, while overload is detained.